Laser printers have high-voltage circuits and high-temperature circuits, so both electronic radiation and thermal radiation have certain influence on human body. We should pay attention to the protection of pregnant women and young children or stay away from these devices. In the printing process, some BLACKPINK particles will be brought out by high temperature heating, which is bad for breathing. Try to avoid working at the laser printer for a long time.

charge

The photoconductor material on the surface of the photosensitive drum is an insulator in the absence of light, in a neutral state, without any charge. To realize the "electrostatic latent image" on the surface of the photoconductor, the surface of the photoconductor must be charged. Only in this way, when the laser beam is scanned onto the photoconductor, the exposed point of the photoconductor is turned on, forming a beam lattice. The dot matrix charge is conducted with the substrate to form a "latent image of potential difference". When the photosensitive drum rotates to a tangent position with the developing magnetic roller, the toner loaded on the magnetic roller with the opposite charge property to the photoconductor surface is attracted to the surface of the photosensitive drum, so that the toner image appears on the photosensitive drum.

To enable the photosensitive drum to absorb carbon powder according to the graphic information, the selenium drum should be charged first. The charging electrode is a tungsten wire parallel to the axis of the photosensitive drum with a DC voltage of 5 ~ 7 kV. When the surface of the selenium drum is very close to the tungsten wire, the surrounding air is ionized to generate corona discharge, which makes the photosensitive drum charged. The positive and negative voltage is determined by the voltage of tungsten wire. If the photoconductive material is Se-Te alloy, it will be positively charged. After the photosensitive drum rotates once, the whole surface will be charged.

The method of laser charging the photosensitive drum varies with different models, but the charging principle is basically the same, and the surface of the photosensitive drum is charged by corona discharge of DC high voltage.

The early laser printers used the composite structure of electrode wire and grid to charge more, and most of the new laser printers used charging cots (FCR) to charge the photosensitive drums. When the high voltage generator sends a high voltage to the electrode wire, a strong electric field is formed between the electrode wire and the grid, and corona is released. The air between the electrode wire and the photosensitive drum is ionized, and the air ions migrate to the surface of the photosensitive drum, so that the surface of the photoconductor (photosensitive drum) is full of charges. This method can make the surface of photoconductor (photosensitive drum) uniformly charged, but at the same time it also produces a lot of negative ions (ozone). When ozone gathers to a certain amount, it is harmful to human body. Such as Canon's early products LBP-SX, ST, HP's early products HP2, 3, Panasonic KX6500 made in Japan, Lenovo LJ6L, LJ6P and other models all use this method to charge.

Most modern laser printers are charged by charging roller. Because of the contact charging method, there is no need for high charging voltage, and no ozone is produced. However, the accumulation of ionized dust increases the wear of photosensitive drum, and there will be uneven charging.